DOI: https://doi.org/10.30795/jfootankle.2021.v15.1228 Original Article Calcaneal stress fractures in civilian patients: an epidemiological study Pedro José Labronici1 , Robinson Esteves Santos Pires2 , Luiz Eduardo Cardoso Amorim3 1. Hospital Santa Teresa, Petrópolis, RJ, Brazil. 2. Universidade Federal de Minas Gerais, Minas Gerais, MG, Brazil. 3. Orthopedics and Traumatology Departament, Faculdade de Medicina da Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil. Abstract Objective: To conduct a retrospective magnetic resonance imaging (MRI) analysis of calcaneal stress fractures and construct an epi- demiological profile of these injuries. Methods: Of 258 MRIs analyzed, nine were consistent with calcaneal stress fractures. These were evaluated by two investigators to confirm the diagnosis. The calcaneus was divided into three anatomical regions: anterior calcaneus (delimited by the angle of Gissane), mid-calcaneus (delimited by the angle of Gissane and tuberosity of the posterior facet), and posterior calcaneus (delimited by the tuberosity of the posterior facet). Fractures were classified as low-grade (grade I, when associated with periosteal edema; II, endosteal; III, muscular) or high-grade (grade IV, when there was a visible fracture line on MRI). Results: The average patient with a calcaneal stress fracture was an overweight (66.7%) female (66.7%) amateur athlete (66.7%), with a left-sided (55.6%) grade IV fracture (77.8%) of the posterior portion of the calcaneus (66.7%), sustained while running (77.8%), and took 1 to 2 years to be diagnosed (66.7%). Conclusion: Calcaneal stress fractures are more frequent in women, amateur athletes, middle age, and in those with overweight. Younger patients usually present with grade I, II, or III fractures, while middle-aged patients present most often with grade IV fractures; lesions tend to be more common in the anterior region than in the mid- or posterior calcaneus. Level of Evidence IV; Therapeutic Studies; Case Series. Keywords: Fractures, stress/epidemiology; Calcaneus/injuries; Magnetic resonance imaging. Introduction of this type of fracture and low level of suspicion, it is diagno- sed rarely as compared to other conditions, such as hindfoot Calcaneal stress injuries were first reported in the German tendinopathy, plantar fasciitis, neuropathies, retrocalcaneal literature in 1937(1,2). Stress fractures are the result of repeti- bursitis, and calcaneal (Achilles) tendinopathy(4). tive microtrauma to normal bone, and have an incidence of Several risk factors have been associated with development 1% to 7% among all sports activities. They are considered the of calcaneal stress fracture, including insufficient physical second most common foot injury, accounting for 20% of all activity and inadequate footwear(12,13). Conventional radiogra- fatigue-induced fractures(3-5). These injuries occur primarily phy, especially in the early stages of these lesions, cannot es- in military recruits, long-distance runners, and the obese. tablish a definitive diagnosis. Instead, bone scintigraphy and Women have a particularly high prevalence, with reports that magnetic resonance imaging (MRI) are considered the most these lesions may account for up to 39% of all fractures in reliable imaging methods for the diagnosis of stress fracture. (3,4,6-11) females . Both modalities have excellent sensitivity, but MRI also offers Heel pain is a common complaint in adults, and can cause high specificity and is considered the optimal imaging me- discomfort and disability. However, due to the low incidence thod for diagnosis of stress fractures(11). Study performed at the Hospital Santa Teresa, Petrópolis, RJ, Brazil. How to cite this article: Correspondence: Luiz Eduardo Cardoso Amorim. 4801 das Américas Av., Loja Labronici PJ, Pires RES, Amorim LE. A. Barra da Tijuca, Rio de Janeiro, RJ, Brazil. Zip Code: 22631-004. Calcaneal stress fractures in civilian patients: [email protected] none. E-mail: Conflicts of interest: Source of funding: an epidemiological study. none. Date received: March 12, 2021. Date accepted: March 30, 2021. Online: April 30, 2021. J Foot Ankle. 2021;15(1):54-9. 54 J Foot Ankle. 2021;15(1):54-9 Copyright © 2021 - Journal of the Foot&Ankle Labronici PJ et al. Calcaneal stress fractures in civilian patients: an epidemiological study The objective of this study was to conduct a retrospective endosteal edema; grade III, muscle edema) or high-grade MRI analysis of stress fractures and outline the epidemiologi- (grade IV) when there was a visible fracture line on MRI(15-17) cal profile of this injury. (Figures 2A, 2B). Because the calcaneus is an essentially tra- becular bone, the low-grade fractures were pooled for analysis by the two investigators, as these lesions are difficult to assess. Methods This study was approved by the Institutional Review Board and registered on the Plataforma Brasil database under Statistical analysis CAAE (Ethics Evaluation Submission Certificate) number: Due to the small sample size, no inferential analysis of 82503418.6.0000.5245. An informed consent form was signed significance could be performed; the statistical analysis was by the patients involved. descriptive, based on graphs, frequency distributions, and calculation of (mean, median, standard deviation, coefficient From January 2015 to December 2017, all MRI scans of pa- of variation – CV – for the age variable). The variability of age tients presenting to the study hospital with hindfoot pain distribution was considered low if , moderate if , and high if. were retrospectively evaluated. Graphs were plotted in Microsoft Excel 2007. All other The exclusion criteria were patients who presented with analyses were carried out in SPSS Statistics for Windows, acute calcaneal fracture or with any infection involving the Version 22.0. ankle and/or foot. Patient charts were analyzed to collect data on demographic parameters and clinical history, inclu- ding time from symptom onset until definitive diagnosis and Results type of activity that triggered heel pain. Of 258 MRIs analy- The baseline sample of this study is composed of nine pa- zed, 11 were consistent with stress fracture, but two were ex- tients with calcaneal stress fractures, six women (67.7%) and cluded because the patients presented with acute trauma. three men (33.3%), as shown in figure 3. Therefore, the sample consisted of nine patients (Table 1). The age distribution of the patients, overall and by gender, Magnetic resonance imaging of the ankle was obtained in is described in table 2. Patient age ranged from 36 to 74 years at least two different planes. Of these, the sagittal and axial (mean, 50.8 years; median, 48.0 years; standard deviation, planes, in T1-weighed spin-echo and fast-spin T2-weighed 11.8 years), and variability was moderate (CV=0.23). The sequences with fat suppression, were the most common. variability of age distributions in the female and male sub- Additional sequences were also requested, such as STIR groups was also moderate. Women with calcaneal stress (short-tau-inversion-recovery). All MRIs were evaluated by fractures were generally older than men (4.2 years on ave- two investigators to certify that they represented stress rage). A comparison of mean and median age in the male and fractures. To determine the location of the lesion, as proposed female subgroups is shown in figure 4. (14), the calcaneus was divided into three by Sormaalaet al. The frequency distribution of variables that characterize pa- anatomical regions: The anterior calcaneus (delimited by the tients and their fractures, overall and stratified by gender, is angle of Gissane), mid-calcaneus (delimited by the angle of shown in table 3. The frequency distribution of age shows Gissane and tuberosity of the posterior facet), and posterior that the most typical age groups for calcaneal stress fractu- calcaneus (delimited by the tuberosity of the posterior facet) res are between 36 and 56 years (66.6%). The typical patient (Figure 1). with a calcaneal stress fracture was an overweight (66.7%) Calcaneal stress fractures were classified as low-grade female (66.7%) amateur athlete (66.7%), with a left-sided (grade I, when associated with periosteal edema; grade II, (55.6%) grade IV fracture (77.8%) of the posterior portion of Table 1. Demographic data and clinical history of the included patients Age Time elapsed from Code Gender Site of fracture Side Meters Weight Bmi Athlete Cause Level (years) symptoms to diagnosis 1 43 Female Posterior portion Right 1,68 62 22,0 About 1 year Amateur Running I, II, III 2 41 Female Posterior portion Left 1,72 75 25,4 About 1,5 year Amateur Running IV 3 46 Male Posterior portion Right 1,78 86 27,1 About 2 years Amateur Running IV 4 62 Male Media portion Right 1,7 84 29,1 About 1 year No Walking IV 5 36 Male Posterior portion Left 1,76 68 22,0 One week Amateur Running IV 6 50 Female Posterior portion Left 1,67 70 25,1 About 10 months No Running IV 7 57 Female Posterior portion Right 1,72 73 24,7 1 Year Amateur Running IV 8 48 Female Media portion Left 1,74 69 22,8 About 6 months Amateur Running IV 9 74 Female Anterior portion Left 1,69 74 25,9 About 1 year No Walking I, II, III J Foot Ankle. 2021;15(1):54-9 55 Labronici PJ et al. Calcaneal stress fractures in civilian patients: an epidemiological study Figure 3. Gender distribution of the sample. Figure 1. Calcaneus divided into three anatomical regions: A – posterior; B – medial; C – anterior. Table 2. Key statistics for the patient age variable, overall and stratified by gender Statistic Overall Female Male Minimum 36 41 36.0 Maximum 74 74 62.0 Mean 50.8 52.2 48.0 Standard deviation 11.8 12.1 13.1 CV 0.23 0.23 0.27 Median 48.0 49.0 46.0 A Figure 4.